An internal combustion engine is known, including a variable compression ratio mechanism capable of varying a compression ratio by changing a combustion chamber volume and a variable valve mechanism capable of varying a valve timing of an intake or exhaust valve such that the compression ratio and the valve timing of the intake or exhaust valve can be controlled according to engine operating conditions.
For example, Patent Document 1 discloses a technique of preventing interference between an intake valve and a piston in such type of engine by determining a maximum compression ratio at which the piston does not interfere with the intake valve at a valve timing set according to engine operating conditions and, when a target compression ratio is higher than the maximum compression ratio, controlling the target compression ratio to the maximum compression ratio.
It is however not possible in the technique of Patent Document 1 to, at the time of increasing an actual intake air amount in response to increase in demand load under the condition that the target compression ratio is high, increase the actual intake air amount by increasing a valve overlap period of the intake and exhaust valves and thereby enhancing cylinder scavenging.
In other words, there is a possibility of interference between the intake valve and the piston in the case where the valve timing of the intake valve is varied so as to increase the valve overlap period of the intake and exhaust valves for the purpose of increasing the actual intake air amount under the condition that the target compression ratio is high.
Prior Art Documents
Patent Document
Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-120464